1. Field of the Invention
The present invention relates to the manufacture of a semiconductor device, and more particularly, to a method of manufacturing a metal-insulator-metal (MIM) capacitor by applying a multi-stepped wet treatment to the surface of a metal electrode of the capacitor in order to improve the characteristics of the capacitor.
2. Description of the Related Art
With the increased integration density and advanced performance of semiconductor devices (e.g., DRAM devices), the design rule of such devices is being markedly reduced. Thus, various methods for manufacturing capacitors that occupy a smaller area of the device and having a larger capacitance have been proposed. One of those methods involves the manufacture of MIM capacitors.
A typical method of forming an MIM capacitor comprises forming a lower metal electrode, forming a dielectric layer, performing a thermal treatment, and forming a metal upper electrode. Here, before the dielectric layer is formed, the lower metal electrode may be placed under certain processes that cause it to suffer from environmental damage. As a result, the processes and related circumstances affect the characteristics of the completed capacitor. That is, exposure conditions, such as atmospheric environment and exposure time, under which the lower metal electrode is placed prior to formation of the dielectric layer, may degrade the characteristics of the capacitor.
In addition, certain processes that are performed prior to the formation of the dielectric layer may degrade the characteristics of the competed capacitor. For example, node separation, which is performed subsequent to formation of the lower electrode, may cause moisture absorption into the surface of the metal electrode. Also, unwanted oxides (e.g., native oxide) may be generated on the surface of the lower metal electrode due to the oxidative environment. Also, organic materials may be absorbed on the metal electrode. As a result of these effects, a junk layer, or junction layer, containing oxygen or carbon is generated on the surface of the metal electrode. This junk layer exhibits intermediate properties between the properties of a metal and a dielectric material and thus is a primary contribution to degradation of the characteristics of the capacitor.
Since the foregoing junk layer increases equivalent oxide thickness and deteriorates interfacial characteristics between an electrode and a dielectric layer, the dielectric layer cannot be properly deposited. Accordingly, the junk layer should be removed during the manufacture of capacitors.